Electrical discharge apparatus.



106-84- -CROSSREFERENCE H M N. J. REALL- ELECTRICAL DIBGHABGE APPARATUS.

' urmonml nLnn IA]. 24. mos.

Patented Oct. 12,1909;

WITNESSES: INVENTOR UNITED 1 STATES PATENT OFFICE.

HEWITT J. HEALL, OF PITTSBUBG, PENNSYLVANIA, A SSIGNOE TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRICAL DISCHARGE APPARATUS.

Specification of Letters Patent.

Patented Oct. 12, 1909.

. Application filed January 24, 1906. Serial No. 297,690.

1; State of Pennsylvania, have invented a new and useful Improvement in Electrical Discharge Apparatus, of which the following is a specification.

My invention relates to devices that are commonly known as lightning arresters, and articularly to discharge or conducting looks that are em loyed m such devices for causing static disc arges to divide among a lar e number of paths. I

he object of my invention isto provide a novel and improved method of forming such dischar e blocks and a novel composition of materia therefor.

One form of lightning arrester heretofore used com rises one or more blocks or plates interpose in the path of a static discharge and roviding a large number of independent disc arge paths, the character of the paths being such that dynamo cufrent is prevented from following a static dischar e. Such dischar blocks have heretofore een composed 0 an intimate mixture of granulated carborundum, or other conducting substance of fixed composition and preferably produeed or disintegrated electro-chemically or at very high temperatures, powdered s ar or other suitable non-conducting matema and water-glass or other binder. The carborun Hum or cbf'nducting substance may also be mixed with shellac. and remain, ma nesi m g and ,m gn $inm.-. h o di i sslal other suitable non-conducting substances that may serve both as fillers and binders, the mixture being the manner in which the binder may be caused to harden. With such mixtures, however, it has been found that while the filler and binder are in a plastic state and before or during the process of hardening, the carborundum particles, because of their greater specific gravity, settle and concentrate in the lower parts of the blocks, thus preventing the formation of blocks of homogeneous texture. It has also been found difficult, in the process of manufacture, to accurately predetermine what has been termed the equivalent spark gaps of such discharge blocks and also the opposition offered by them to'the passage of d namo currentafter d scharges. The equiva ent spark gap of a dried or baked, according to circuit may be determined by connecting an air-gap in shunt to the circuit and adjusting the gap until discharges will occur across it as readily as through the circuit. To over'- come the above-mentioned difiiculties, I propose to form the carborundum or conducting material into pellets or b6dies and to coatthem with an insulating material that is preferably porous. Inasmuch as the pellets or bodies are rovided with insulating shells or coatings be ore being mixed with the plastic binding and filling material, a suilicient number may be employed to insure. contact between the shells of adjacent ellets and, consequently, a. uniform istribution throu hout the mass. The equivalent spark gap of each pellet or body and its ability to oppose the passage of d namo current may be accurately determine and, consequently, the same characteristics may be determined for a complete block composed of ellets that are in contact with each other, i the thickness of the pellets and of the block is known. Y

Figure 1 of the accompanying drawing is a transverse, sectional view through a device that embodies my invention, and Fig. 2 is an enlarged sectional view of one -of the conducting bodies of which the discharge block comprlsing' my invention is composed.

A flat, cylindrical discharge block 1 is provided with dished or recessed faces with which correspondin 1y shaped conducting plates 2 and 3 are a apJted to enga e and to which they are prefera ly cemented, each of the plates being provided with a pair of studs or bosses 4 that are punched therefrom or that are formed in any other suitable manner, the exposed edges of the block being preferably enameled to prevent the absorption of moisture. A conduct' lead 5, that is adapted to be connected to t e ground, is soldered or otherwise connected to' the plate 3. The block I and the plates 2 and 3 are supported in position between blocks 6 and 7 :vf porcelain or other insulating material, the inner faces of which are provided with recesses 8 into which the bosses Lproject for the purpose of preventing relative dis lacement of the engaging parts. A piece 0 suitable insulating material 9, such as fish-paper or fuller-board, is interposed between the block 7 and the plate a and a gasket 10 is interposed between the block 7 and the inner ace of the lower half'of an inclosiifg and supporting casing 12, both being for the urpose of afl'ording cushions for the insuating block 7.

One or more sheets 13 of suitable insulating material, such as mica, having central apertures 14, are placed between the porcelain block 6 and the plate 2, and a dishshaped plate 15, that is located in a central recess 16 in the block 6, is laced with its concave face toward the insu ating piece 13. The plate 15 is provided with a central boss 17 that is punched therefrom or formed in any other suitable manner and that is located directly over the apertures 14 in the mica sheets 13, an air-gap being thereby provided between the boss 17 and the plate 2. The width of the air-gap may be adjusted by varying the number or thickness of the mica sheets. The parts are all clamped together by means of a set-screw 19 that is threaded into a rib 20in the interior of the lower half of the inclosing casing 12. A dish-shaped plate 21 having a central aperture through which a reduced portion 22 of the set-screw projects and that is laced with its concave face toward the in ating block 6, serves as a wearing piece and affords mechanical protection to the insulating block 6, a gasket 23 being interposed between the late 21 and the block .6 for the purpose 0 affording a cushion for the block.

The discharge block 1 is composed of a large number of pellets or bodies 24 of conducting material, such as carborundnm, provided with coatings Lg: an insulatlng and preferably porous ma erial 25, such as cla that are hardened upon the bodies before e block is formed. The pellets or bodies may be bound together by means of a suitable insulating material 26, such as fireclav, waterlass a mixture of ma esium 0x18 and ma 'n lor'd, cemenI and shellac e 0e mg e1 er or %amu&ked accordin to the character the to cause Tmrdeniug thereof. The equivalent spark gaps and the capability of single pellets and of two or more pellets in series to oppose the passage of dynamo current may be measured and, if the diameters or thicknesses of the llets and the thickness of the'discharge b ock are known,similar characteristics thereof may be accurately predetermined, so that the blocks may be readily formed to conform to the voltage, current and other conditions of the circuit in connection with which the device is to be employed. when so constructed, the blocks will also be uniform in texture throughout their thickness.

It is conceivable that blocks or plates having the structural and electrical characteristics herein described may be advantageously utilized in other relations and for other specific purposes, and I therefore desireand intend to include within the scope of my invention all blocks or plates having the structural and functional characteristics herein described, whatever may be the particular service in which they are em loyed.

It will be understood that the bloc s may be composed of pellets the coatings u on which are not first hardened, or the pellets may be unprovided with coatings and mixed with non-conducting fillers and binders and thereby maintained out of contact with each other substantially in the same manner as is effected by the coatings.

I claim as my invention:

1. A block composed of electrical conducting bodies having individual coatings of insulating material and bound together by other insulating material in which they are embedded.

2. A block composed of electrical conducting bodies having individual coatings of porous insulating material and bound together by other insulating material in which they are embedded.

3. The method of forming blocks or plates for electrical discharge devices which consists in forming a conducting material into a plurality of bodies, providing such bodies with individual coatings of insulating material and binding the bodies together by other insulating material.

4. The method of forming blocks or plates for electrical discharge devices which consists in forming a conducting material into a plurality of bodies, coating the bodies individually with. porous insulating material and bindin the coated bodies together by porous insu ating material.

5. The method of forming blocks or plates for electrical discharge devices, which consists in forming conducting material into pellets, coating the pellets individually with insulating material, hardening the insulating coatings, binding the coated pellets together in a plastic insulating material and hardenin the insulating binder.

6. A b ock composed of bodies of hig resistance conductmg material individua ly coated with insulating material and bound together by other insulating material inwhich they are embedded.

7. A block composed of bodies of refractory conducting material individually coated with insulating material and bound together by other insulating material in which they are embedded.

In testimony whereof, I have hereunto subscribed my name this 18th day of J anuary, 1906.

NEWITT J. NEALL.

Witnesses:

R. B. INGRAM, BIBNEY HINES. 

